1. Field of the Invention
The present invention relates generally to a semiconductor integrated circuit having a fuse. More particularly, the invention relates to a semiconductor integrated circuit that, even when components such as circuits and elements near a fuse are damaged during fuse blowing, is capable of exhibiting an appropriate function equivalent to that obtainable in the event of appropriate fuse blowing.
2. Description of the Related Art
In recent years, a semiconductor integrated circuit uses nonvolatile memory devices each containing a fuse and the like and programs the memory devices, thereby to set redundant-memory replacement data, operation modes, and the like. In addition, recently, by way of a mainstream programming method, a fuse formed of a metal or the like is irradiated with a laser beam to be vaporized, whereby the conduction in a fuse portion is cut off. That is, a so-called “laser fuse method” for performing fuse-blowing programming is a recent mainstream programming method. Such techniques are disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication Nos. 7-211779, 11-90659 and 2001-57388.
In recent years, techniques such as high integration and micro-fabrication of semiconductor integrated circuits are noticeable. Under such circumstances, in a circuit requiring programming to be performed according to the laser fuse method using an ordinary laser beam is constructed, there is a high risk that the circuit does not appropriately operate because of fuse blowing. More specifically, suppose a gate and the like of a transistor provided near a lower layer of the fuse are caused to shrink (reduced in size or miniaturized). In this case, a laser beam energy occurring at fuse blowing causes an oxide film, diffusion layer, and the like of the transistor to easily break. With such the oxide film or diffusion layer of the transistor being broken, the transistor accordingly is caused not to appropriately operate. This can potentially cause the entirety of the semiconductor integrated circuit not to appropriately operate.